Feminizing hormone therapy is used to induce physical changes in your body caused by female hormones during puberty (secondary sex characteristics) to promote the matching of your gender identity and your body (gender congruence). If feminizing hormone therapy is started before the changes of male puberty begin, male secondary sex characteristics, such as increased body hair and changes in voice pitch, can be avoided. Feminizing hormone therapy is also known as gender-affirming hormone therapy

During feminizing hormone therapy, you'll be given medication to block the action of the hormone testosterone. You'll also be given the hormone estrogen to decrease testosterone production and induce feminine secondary sex characteristics. Changes caused by these medications can be temporary or permanent. Feminizing hormone therapy can be done alone or in combination with feminizing surgery.

Feminizing hormone therapy isn't for all transgender women, however. Feminizing hormone therapy can affect your fertility and sexual function and cause other health problems. Your doctor can help you weigh the risks and benefits.

Feminizing hormone therapy is used to alter your hormone levels to match your gender identity. Typically, people who seek feminizing hormone therapy experience discomfort or distress because their gender identity differs from their sex assigned at birth or sex-related physical characteristics (gender dysphoria). To avoid excess risk, the goal is to maintain hormone levels in the normal range for the target gender.

Feminizing hormone therapy can:

• Make gender dysphoria less severe
• Reduce psychological and emotional distress
• Improve psychological and social functioning
• Improve sexual satisfaction
• Improve quality of life

Research suggests that feminizing hormone therapy can be safe and effective.

If used in an adolescent, hormone therapy typically begins at age 16. Ideally, treatment starts before the development of secondary sex characteristics so that teens can go through puberty as their identified gender. Many trans girls are treated with a medication to delay the start of puberty. Gender affirming hormone therapy is not typically used in children.

Feminizing hormone therapy isn't for all trans women. Your doctor might discourage feminizing hormone therapy if you:

• Had or have a hormone-sensitive cancer, such as prostate cancer
• Have a thromboembolic disease, such as when a blood clot forms in one or more of the deep veins of your body (deep vein thrombosis) or a blockage in one of the pulmonary arteries in your lungs (pulmonary embolism)
• Have uncontrolled behavioral health conditions
• Have uncontrolled significant medical conditions
• Have a condition that limits your ability to provide informed consent

Talk to your doctor about the changes in your body and any concerns you might have. Complications of feminizing hormone therapy might include:

• A blood clot in a deep vein (deep vein thrombosis) or in a lung (pulmonary embolism)
• High triglycerides, a type of fat (lipid) in your blood
• Weight gain
• Infertility
• High potassium (hyperkalemia)
• High blood pressure (hypertension)
• Type 2 diabetes
• Cardiovascular disease
• Excessive prolactin in your blood (hyperprolactinemia)
• Nipple discharge
• Stroke
• Increased risk of breast cancer compared to men whose gender identity and expression matches the stereotypical societal characteristics related to their sex assigned at birth (cisgender men)

Your fertility

Because feminizing hormone therapy might reduce your fertility, you'll need to make decisions about future childbearing before starting treatment. The risk of permanent infertility increases with long-term use of hormones, especially when hormone therapy is initiated before puberty. Even after stopping hormone therapy, testicular function might not recover sufficiently to ensure conception without reproductive technology assistance.

If you want to have biological children, talk to your doctor about freezing your sperm (sperm cryopreservation) before beginning feminizing hormone therapy.

Other side effects of estrogen use in trans women include reduced libido, erectile function and ejaculation. Erectile function might improve with the use of oral medications such as sildenafil (Viagra) or tadalafil (Adcirca, Cialis).

Before starting feminizing hormone therapy, your doctor will evaluate your health to rule out or address any medical conditions that might affect or contraindicate treatment. The evaluation might include:

• A review of your personal and family medical history
• A physical exam, including an assessment of your external reproductive organs
• Lab tests measuring your lipids, blood sugar, blood count, liver enzymes, electrolytes and the hormone prolactin
• A review of your immunizations
• Age- and sex-appropriate screenings
• Identification and management of tobacco use, drug abuse, alcohol abuse, HIV and other sexually transmitted infections
• Discussion about sperm freezing (sperm cryopreservation)
• Discussion about use of potentially harmful treatment approaches, such as unprescribed hormones, industrial-strength silicone injections or self-castration

You might also need a behavioral health evaluation by a provider with expertise in transgender health. The evaluation might assess:

• Your gender identity and gender dysphoria
• The impact of your gender identity at work, school, home and social environments, including issues related to discrimination, relationship abuse and minority stress
• Mood or other mental health concerns
• Sexual health concerns
• Risk-taking behaviors, including substance use and use of nonmedical-grade silicone injections or unapproved hormone therapy or supplements
• Protective factors such as social support from family, friends and peers
• Your goals, risks and expectations of treatment and your future plans for your care

Adolescents younger than age 18, accompanied by their parents or guardians, also should see doctors and behavioral health providers with expertise in pediatric transgender health to discuss the risks of hormone therapy, as well as the impact and possible complications of gender transition in that age group.

During the procedure

Typically, you'll begin feminizing hormone therapy by taking the diuretic spironolactone (Aldactone) at doses of 100 to 200 milligrams daily. This blocks male sex hormone (androgen) receptors and can suppress testosterone production.

After four to eight weeks, you'll begin taking estrogen to decrease testosterone production and induce feminization. Estrogen can be taken in a variety of methods, including as a pill, by injection or in skin preparations, such as a cream, gel, spray or patch. Don't take estrogen orally, however, if you have a personal or family history of venous thrombosis. Use of gonadotropin-releasing hormone (Gn-RH) analogs to suppress testosterone production might allow you to take lower estrogen doses and wouldn't require the use of spironolactone. However, Gn-RH analogs are more expensive.

Additional therapies might include:

• Progesterone that's been reduced to tiny particles (micronized), which might improve breast development
• Finasteride (Propecia) or topical minoxidil (Rogaine) or both for people prone to male-pattern baldness

Feminizing hormone therapy will begin producing changes in your body within weeks to months. Your timeline might look as follows:

• Decreased libido. This will begin one to three months after starting treatment. The maximum effect will occur within one to two years.
• Decreased spontaneous erections. This will begin one to three months after treatment. The maximum effect will occur within three to six months.
• Slowing of scalp hair loss. This will begin one to three months after treatment. The maximum effect will occur within one to two years.
• Softer, less oily skin. This will begin three to six months after treatment.
• Testicular atrophy. This will begin three to six months after treatment. The maximum effect will occur within two to three years.
• Breast development. This will begin three to six months after treatment. The maximum effect will occur within two to three years.
• Redistribution of body fat. This will begin three to six months after treatment. The maximum effect will occur within two to five years.
• Decreased muscle mass. This will begin three to six months after treatment. The maximum effect will occur within one to two years.
• Decreased facial and body hair growth. This will begin six to 12 months after treatment. The maximum effect will occur within three years.

During your first year of feminizing hormone therapy, you'll need to see your doctor approximately every three months for checkups, as well as anytime you make changes to your hormone regimen. Your doctor will:

• Document your physical changes
• Monitor your hormone concentration, and use the lowest dose necessary to achieve desired physical effects
• Monitor changes in your lipids, fasting blood sugar, blood count, liver enzymes and electrolytes that could be caused by hormone therapy
• Monitor your behavioral health

You will also need routine preventive care, including:

• Breast cancer screening. This includes monthly breast self-exams and age-appropriate mammography screening according to the age-appropriate breast cancer screening recommendations for cisgender women.
• Supplementation. This includes standard calcium and vitamin D supplementation, along with bone density assessment according to the age-appropriate recommendations for cisgender women.
• Prostate cancer screening. This should be done according to age-appropriate recommendations for cisgender men. With estrogen treatment, your PSA level is expected to decrease by about 50 percent.